Neural and behavioral development is characterized by two features. First, brain and behavior are organized by an interplay of genetic instruction and information from the environment. Second, the acquisition of external information is, in many cases, not a steady process. Instead, information is often acquired only for a limited time span, the sensitive period. During development, an animal may experience many of these sensitive periods, all of them needed for a distinct purpose. The basic features of such sensitive periods are described, and the neurophysiological basis of the neuronal rewiring that underlies the acquisition of early learning is discussed. An example is presented which may serve as a general scenario for early learning in sensitive periods.